1. Field of the Invention
The present invention relates to a wiring substrate which electrically or mechanically connects a semiconductor integrated circuit or a circuit substrate, and a semiconductor device using the wiring substrate.
2. Description of the Related Art
Prepreg in which a sheet-like fibrous body as a reinforcing material is impregnated with a thermosetting resin and the thermosetting resin is made in a semi-cured state has been used as a member of a circuit substrate and the like. For example, prepreg is known in which a conductor passes through an insulating layer and which is formed by opening a through hole in a predetermined position and filling the through hole with a conductive paste to become the conductor by hot pressing (see Patent Document 1). In this case, the through hole is opened in the prepreg by a laser, a drill, a punching machine, or the like.
Further, prepreg used as a sealing material of a semiconductor device is disclosed (see Patent Document 2).